[ka7niq]

I have my VMPS RM 40's passively biamped.
I am using a big modified "pro sound" amp on the woofers, and a Luxman M 117 on the ribbons.
Because I didn't know how this was going to work out, I was reluctant to invest in expensive wire.
So, I just used Radio Shack 18 guage wire on the Luxman, and 14 guage on the woofers/amp.
It sounded great, once I got the levels right.
Then, I went and got some 12 guage wire , and put this on the woofers, and took the 14 guage, and put it on the ribbons.
I could tell no difference in the bass, but the midrange lost it's warmth!
It didn't sound bad, just not as good as the smaller 18 guage wire!

So, I then took the 12 guage, and put IT on the ribbons, leaving the 14 guage on the woofers.

It sounded worse than the 14 guage on the ribbons!

So, I went back to the 18 guage on the ribbons, and left the 14 goage on the woofers.
I returned the 12 guage ...

I do plan to try some 10 guage on the woofers, just for kicks.
But I started searching for a rational explanation as to WHY the small 18 guage sounds better on the ribbons ?

Theory tells us that smaller wire has higher resistance, and CAN exhibit a bit of power loss in longer runs, especially with a low impedence speaker.

But this small amount of power loss is easily overcome by simply increasing level.
Something else HAS to be going on, and I think I may have found the answer.
This link  http://www.bcae1.com/dampfact.htm has a chart where one can easily the effect on DAMPING FACTOR wire resistance has.

What is going on is that the smaller wire is reducing the damping factor of the amp/ribbon interface!

Tube amps have lower damping factors then solid state ones do, but Tube amps can sound mighty good.

Some big Krells and Crowns have damping factors of over 1000, and we all KNOW how they sound, right ?

I am going to even try 24 guage wire on my ribbons, but 18 guage is todays shoot out winner.

This is an EXPENSIVE experiment to try, it will cost you 4.95 for a 25 foot spool of Radio Shack 18 guage red/black speaker wire.

It may, or may not work with YOUR amp, but the Luxman M 117 loves it.

And, so do the RM 40 ribbons.
They take on a smooth, almost tube like magic, and just sound fuller, to my ears.

Yes, the larger wire is a BIT more detailed, but the fullness and musicality is better with the smaller wire.

Imaging is better with the smaller wire too, and seems more "believable".

Just wanted to share this with all
Chris

[john1970]

Chris,

Thank you for the link for the damping factor calculator.  I always find it amuzing how much even short runs of thick cables decreases the damping factor.  I currently run 10ft. of 10 ga Belden cable to each of my VMPS RM40s.  Even though the amp I use has a rated damping factor of 750 (8 ohms) the actual damping factor seen by the VMPS bass drivers (3.5 ohm impedence) is ~140. 

Cheers,

John

P.S.  On the Supermax OXO crossover Brian uses a very thin cable on the tweeters, and medium gauage cable on the midrange panels, and a thick cable going to the bass drivers. 

[ka7niq]

Chris,

Thank you for the link for the damping factor calculator.  I always find it amuzing how much even short runs of thick cables decreases the damping factor.  I currently run 10ft. of 10 ga Belden cable to each of my VMPS RM40s.  Even though the amp I use has a rated damping factor of 750 (8 ohms) the actual damping factor seen by the VMPS bass drivers (3.5 ohm impedence) is ~140. 

Cheers,

John

P.S.  On the Supermax OXO crossover Brian uses a very thin cable on the tweeters, and medium gauage cable on the midrange panels, and a thick cable going to the bass drivers. 

Hello John!
Nice to hear from you.
I was out listening tothe RM 40's, and watching my Tigers get beat, so far.
It;s bottom of the 5th inning, and St. Louis is ahead 4 to 1.

God my speakers have never sounded better, you just can't imagine how much difference passive biamp makes over just one amp.
With the midrange pot all the way on, it must be out of the circuit, so to speak, because the riibbons take on a whole new majic.

The big Ashly FET 500 is doing a valiant job down below on the woofers, and the tube like Luxman M 117 is sweet up top, at least with the smaller wire.
I AM going to get some bigger cable for my woofers.
I ran my tweeters down from wide open, but the mids are cranked all the way open.
I use the Luxman M 117's level controls to get my balance between the ribbons and the woofers.

The ribbons seem WAY more effecient then the woofers, a good thing.
That will allow a smaller tube amp. something really thick and 3 dimensional like an old Conrad Johnson MV 75 to power the ribbons.

I have to go to my friend Mikes home and p/u my other Ashly.
I wanna run em bridged on my woofers, about 1200 watts into 4 ohms bridged.

That is interesting that Brian runs smaller wire up top on his new crossovers ?
I am sure he listened  for a long time before he made his choice.

Well, the food is out of the Microwave, a leftover Cuban Sandwich and some Spanish Bean soup!

Time to go feed my face, listen some more, and watch the World Series.

Later Bro!
Chris

[BrunoB]

Theory tells us that smaller wire has higher resistance, and CAN exhibit a bit of power loss in longer runs, especially with a low impedence speaker.

But this small amount of power loss is easily overcome by simply increasing level.
Something else HAS to be going on, and I think I may have found the answer.
This link  http://www.bcae1.com/dampfact.htm has a chart where one can easily the effect on DAMPING FACTOR wire resistance has.



Tube amps have lower damping factors then solid state ones do, but Tube amps can sound mighty good.

Some big Krells and Crowns have damping factors of over 1000, and we all KNOW how they sound, right ?

One often overlooked resistance is the resistance of the XO inductor placed between the speaker terminals and the woofer.
A typical value would be 0.1-0.2 ohms, which is about equivalent to 50 ft of 14g speaker wire (based on
"If you use 5ft of 14g speaker wire, the total resistance of the wire is .016 ohms."  from http://www.bcae1.com/dampfact.htm).

Also, increasing the resistance between woofer and amp can increase the amount of bass heard  . This is quite unintuitive but here comes the explanation: the amp has less control on the woofer, the woofer generates more distorsions and thus more sound. The sound becomes warmer. I think that tube amps are warmer because of the lower woofer control.

Not being a speaker designer, I am not completely sure about what I wrote above, so feel free to correct me if I am wrong.


Bruno

[ka7niq]

Theory tells us that smaller wire has higher resistance, and CAN exhibit a bit of power loss in longer runs, especially with a low impedence speaker.

But this small amount of power loss is easily overcome by simply increasing level.
Something else HAS to be going on, and I think I may have found the answer.
This link  http://www.bcae1.com/dampfact.htm has a chart where one can easily the effect on DAMPING FACTOR wire resistance has.



Tube amps have lower damping factors then solid state ones do, but Tube amps can sound mighty good.

Some big Krells and Crowns have damping factors of over 1000, and we all KNOW how they sound, right ?

One often overlooked resistance is the resistance of the XO inductor placed between the speaker terminals and the woofer.
A typical value would be 0.1-0.2 ohms, which is about equivalent to 50 ft of 14g speaker wire (based on
"If you use 5ft of 14g speaker wire, the total resistance of the wire is .016 ohms."  from http://www.bcae1.com/dampfact.htm).

Also, increasing the resistance between woofer and amp can increase the amount of bass heard  . This is quite unintuitive but here comes the explanation: the amp has less control on the woofer, the woofer generates more distorsions and thus more sound. The sound becomes warmer. I think that tube amps are warmer because of the lower woofer control.

Not being a speaker designer, I am not completely sure about what I wrote above, so feel free to correct me if I am wrong.


Bruno

Yes, Inductors do make a difference.
Many so called high end speakers do not even use air core inductors.
I once loooked inside a speaker that sold for lots of money, and was shocked to find cheap mylar caps, and non air core coils.

Iron core inductors can easily saturate at high power levels and ruin the party!

I cannot believe  that I am running my RM 40's in this large room, and w/o any subwoofers either.

I do have a SVS Ultra sub I picked up locally in a speaker trade/deal,  but I haven't a pressing need to fire it up.

I think I will throw the tube DAC in the system, I had been using the stock DAC.

Yeah, that will give me something to do this evening, I am bored ...

[Brian Cheney]

Aircores above about 1.5mH have a DCR that is too high for use in a high quality LF crossover like the bass on the RM 40.  We like the 14 gauge Erse SuperQ laminate coils for this reason.  They are very large, don't saturate under 800W input, and have a DCR around .12 Ohms.  In addition they don't have the large stray fields of the aircores. 

We use aircores on the trebles where the values are small.

[SCooper]

I use a 10 ga. air core on the bass section.  DCR .16 . Mounted in external XO box.  Improved the lower end greatly over the "standard" coil.       

[ka7niq]

Aircores above about 1.5mH have a DCR that is too high for use in a high quality LF crossover like the bass on the RM 40.  We like the 14 gauge Erse SuperQ laminate coils for this reason.  They are very large, don't saturate under 800W input, and have a DCR around .12 Ohms.  In addition they don't have the large stray fields of the aircores. 

We use aircores on the trebles where the values are small.

I see.
Hey Brian, two quick questions, can I bring in my spiral RM 40 ribbons tweeters a BIT lower in frequency ?
And, will the mid woofer update give a warmer sound so I can run my ribbons up in level a bit ?

Or, should I wait for a waveguide for the spiral RM 40 ?

MY old Spiral RM 40's have no switch in back, you have to bi wire, biamp, or use jumpers.

Do you recall their crossover point, 200 hz ?

Mine are TRT's ...

[John Casler]

If I remember correctly the xo point on those was around 155Hz or 166hz.

B, can firm that up, but that is what sticks in my mind.

Only after the FST was available did B, move xo's up to 200Hz-280Hz

[BrunoB]

Aircores above about 1.5mH have a DCR that is too high for use in a high quality LF crossover like the bass on the RM 40.  We like the 14 gauge Erse SuperQ laminate coils for this reason.  They are very large, don't saturate under 800W input, and have a DCR around .12 Ohms.  In addition they don't have the large stray fields of the aircores. 

We use aircores on the trebles where the values are small.

The Erse super Q  inductors look small compared to theses:
http://www.mundorf.com/english/bauteile/spulen/null-ohm.htm#baureihen


Some big aircore inductors:
http://www.northcreekmusic.com/NorthCreekCoilPrices.PDF


Bruno

[ka7niq]

If I remember correctly the xo point on those was around 155Hz or 166hz.

B, can firm that up, but that is what sticks in my mind.

Only after the FST was available did B, move xo's up to 200Hz-280Hz

I would like to do a mid woofer update, and raise the crossover on mine.
I would also like to explore crossing over to the spiral ribbon tweeters below 10K, IF possible ?

[John Casler]

If I remember correctly the xo point on those was around 155Hz or 166hz.

B, can firm that up, but that is what sticks in my mind.

Only after the FST was available did B, move xo's up to 200Hz-280Hz

I would like to do a mid woofer update, and raise the crossover on mine.
I would also like to explore crossing over to the spiral ribbon tweeters below 10K, IF possible ?

Hi Chris,

I think you should sell all the rest of your speakers, keep the current pair of RM40s and use one for a Center channel, and then get a new pair of RM40s with all the fixins'.

Then you would have the most incredible frontal array one could ask for, for your HT, and the 2 channel would have all the xover points and woofage factors you crave. aa

[ka7niq]

If I remember correctly the xo point on those was around 155Hz or 166hz.

B, can firm that up, but that is what sticks in my mind.

Only after the FST was available did B, move xo's up to 200Hz-280Hz

I would like to do a mid woofer update, and raise the crossover on mine.
I would also like to explore crossing over to the spiral ribbon tweeters below 10K, IF possible ?

Hi Chris,

I think you should sell all the rest of your speakers, keep the current pair of RM40s and use one for a Center channel, and then get a new pair of RM40s with all the fixins'.

Then you would have the most incredible frontal array one could ask for, for your HT, and the 2 channel would have all the xover points and woofage factors you crave. aa

It would be kinda hard to watch movies with an RM 40 in the way in the center, LOL
BUT, I could simply put the RM 40 on it's side ...